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Forgetting

We've had a look at how things get into the memory, and now we shall look at how they get out or rather forgetting.

Displacement

Firstly, you must know that this is a theory regarding short term memory only. As the multi-store model says, the STM only has a capacity of 7 +/- 2 items. Therefore, when the capacity gets to the maximum, any new information will have to push out the old information; and so it is lost. Evidence for this can be seen in the primacy - recency effect.

Trace Decay

This is a theory of forgetting in short and long term memory. In this theory memories have a physical basis or trace; and over time this trace distintergrates. A bit like how a sandcastle falls apart as the tide comes in.

Below are a pair of studies into trace decay in short term and long term memory.

Study

Decay in Short Term MemoryReitman (1974)

Decay in Long Term MemoryMckenna and Glendon

Aim

Investigate whether decay could cause forgetting

To investigate if memories decay over time

Method

Male students were shown a list of five words for 2 seconds. They then listened out for a faint tone through a pair of headphones (given at 15 seconds).

Then they tried to recall the words.

215 shop and office workers volunteered to take part in a task where they learnt CPR (first aid to restart the heart).

After the training their performance was measured up to 3 years after learning.

Results

Word recall fell by 24% over the 15 second interval

After three months performance had fell sharplyAfter three years performance was very poor.

Conclusions

As the tone detection task required effort thus preventing memorizing the words but no new information was recieved; then the loss must have been due to decay.

Skills such as resuscitation require frequent refreshing to remain good.

Hence time causes the decay of long term memories.

Evaluation

Cannot be sure that no new information was recieved.

Rehearsal may have taken place whilst waiting for the tone, despite what the researchers assumed.

Some memories are very resistive to long-term decay, i.e. there are some things that we remember well even after many many years.

This has very good ecological validity (is very life-like) because this is a real-life situation.

Interference

Proactive interference; where previous interferes with present learning. For example, if you move an item's place, you keep going back to where it used to be.

Retroactive interference which is the opposite: present learning interferes with previous learning. For example, start using a new password, but when you have to remember the old one for another account: you can't.

Evidence comes from paired associates tasks, where a participant has to remember pairs of words (e.g. pen - sock; paper - can) in one group, and then another group with the 'stem' word the same (e.g. pen - shoe; paper - cat). They are then asked to remember the second word when given the first.What was found was that the participant got confused between the two groups of word.

The problems with this theory are that it describes rather than explains why we forget something; it is not hugely applicable to everyday life because we rarely associate two things with one stimulus. And finally, the effects of this forgetting disappear when given a cue.

Retrival Failure

Also known as cue-dependent forgetting this is another type of forgetting only in long term memory.

The idea behind this theory is that you remember a great deal of information in the LTM, but you just can't access it because you do not have adequate retrival cues, and if you are given the cues you will eventually remember. This is seen in everyday life when something is 'on the tip of your tongue', you know that you know it; but just can't remember, once someone helps you out you suddenly realise it.

Below are two studies investigating this type of memory, the one involving divers is very easy to understand because it is so bizare.

Study

Context Dependent MemoryGodden and Baddeley (1975)

Retrival CuesTulving and Osler (1968)

Aim

To investigate the effects of learning environment on recall.

To investigate the effect of retrival cues on recall.

Method

A group of divers was taken, half of them went underwater and half on the beach where they learnt some words.

After this half of those underwater went to the beach and half stayed underwater and likewise for those who learnt on the beach; here they were tested on their recall of the words.

A large gorup of high school students were given a list of paired words to remember that were weakly related. (e.g. sky - clear).

They then were tested on these words by either free recall (coming up with whatever they could think of) or cued recall (where the first word was given).

Results

Words learned under water were recalled best underwater and the same for on the beach.

Cued recall was more successful than free recall.

Conclusions

The environment where something was learnt is very important, possibly because it provides cues that are associated with the word.

Cues 'attached' to the memories facilitate memory.

Evaluation

The differences between the two environments are very extreme and smaller differences (i.e. between a classroom and exam room) have less impact on recall.

This theory is very similar to interference with respect to the use of cues. However, research by Tulving and Psotka (1971) found there was interference in paired associate (two linked words city - dirty) tasks, however, these effects disappeared after being cued, suggesting that interference hasn't really occured because it was merely the problem of accessing the information rather than its availability.